This type of heavier pruning is used to reinvigorate and restore the structure of a damaged, diseased or neglected tree.
Such major pruning should be spaced out over two or three years.
- Heavier pruning cuts should be made in spring, followed by light, corrective pruning in summer.
- Start by thinning the canopy by cutting a few primary and secondary branches which are too big.
- Make cuts diagonally, following the natural angle formed by the branch bark ridge (the wrinkled area on the top of the branch) and the branch collar (the swelling at the base of the branch). Be careful not to damage the ridge or collar, because they contain substances the tissues need to heal.
- Correct any major defects: broken branches, sprouts, suckers, double leaders, and strangulations. Do not leave any stubs.
- Remove any branches that are too low (less than 1 meter off the ground).
- Cut any diseased branches back to healthy tissue (10 cm below the canker or discoloured bark); disinfect the tools between each cut with isopropyl alcohol (rubbing alcohol).
- Do not fill cracks and do not apply any wound dressing (tar, gum, paint, etc.). Such products can be harmful to plants, by creating conditions that encourage insect pests and disease.